1. Field of Invention
This invention relates to the requirements for seating in high-performance vehicles, specifically to a simplified method for creating an accurate form-fit in the types of seats currently used in such applications.
High-performance vehicles typically have the ability to change speed and direction very rapidly. The driver/pilot feels this action as if the body were being pushed violently this way and that by the seat and safety belts. When maximum speeds are attempted, even a few minutes of such activity can be exhausting to the uninitiated. However, some competitive events last for hours. Seating that can provide superior comfort will therefore improve endurance, overall performance, and ultimately safety.
The need to make spontaneously calculated and deliberate but discreet control inputs, in spite of rough conditions, while in hazardous exploration of the machine's performance limits requires seating that precisely locates the driver's body with reference to the vehicle's controls. Therefore proper seating must not only spare the body from unnecessary punishment, but comfort must be achieved without compromising control, and also without insulating the driver from vital sensory feedback of the machine's limits. This invention addresses that need.
2. Description of Prior Art
The first turn at the Indianapolis Motor Speedway is banked at only 13 degrees but drivers there routinely see lateral accelerations from cornering that reach 2.4 G. Grand Prix-type racing boats are said to generate 4 G. turning corners. The fastest drag-racing vehicles currently have peak accelerations that reach nearly 5 G. Even simple racing karts (competition go-karts) record 1.6 G. in steady-state cornering on level asphalt, approximately twice the lateral force a modern passenger car can achieve. Very high-banked turns, vibration from engines, rough track conditions, and accidents all increase the rate and magnitude of forces delivered to the driver's body dramatically.
While it might seem best to provide the maximum mount of soft cushioning to protect the driver/pilot from such a beating, the most successful racing drivers are unanimous in desiring an absolute minimum of cushion. The physical feedback necessary to sense the dynamic limits of the vehicle is often said to originate at the "seat of the pants" and soft cushioning is found to insulate the driver from the reactions of the vehicle to control inputs.
Each form of racing has it own particular constraints in regard to seating. Open-wheeled cars of the Grand Prix, Indy, or Formula type have cockpits that are very tight around the body of the driver, and require a semi-reclining driving position. A few top drivers at this level of motorsport are provided by their teams with individually-made custom-fitted seats to maximize the driver's ability and endurance as well as provide the best protection against accidents. These seats have been produced by customizing standard design seats or by creating molds of the individual driver's body either in plaster bandages, or by the utilization of specially-shaped bags containing loose styrene beads that are vacuumed to create a rigid female mold so that a male impression of the driver's torso can then be obtained for the purpose of creating an appropriate shell in either glass fiber or carbon fiber. Although the custom-fitted seat produced by such techniques appears to be a good solution to the problem of high-performance vehicle seating, the complication, technical skill, and equipment required to produce such seats has made them unavailable or cost-prohibitive to all but the most highly-paid drivers.
A further drawback is that the final result of such methods, being a third-generation image of the driver's body, may not be entirely satisfactory either in terms of precise fit or because the original mold, having been created outside the actual relationship of the driver to the controls (steering wheel, pedals, shifter, etc.) may not produce an ideal ergonomic relationship to control the vehicle. Therefore, although the fit may allow the driver to resist dynamic forces adequately, the body position may resist being harmonized with the controls, producing debilitating fatigue and reduced performance over time.
It is also significant that the actual body support produced by such methods is derived from molds of the anatomy taken while the flesh is slumped by gravity. This is inferior to what could be achieved by capturing a mold of the body while positive pressure is applied over that surface of the body which is to be supported by the seat. Such a positive-support seat form would also serve to precompress the soft portions of the anatomy, as in the kidney area, and provide greater resistance to injury from shocks or accidents.
An inexpensive and widely-known method for fitting a driver to a single-seat-type vehicle where the driver has no separate seat but simply reclines in a narrow area formed by the structural panels of the chassis, is to have the driver sit on a large household-type polyethylene trash bag that has had a mixture of reacting polyurethane foam placed inside. The expansion of the foam creates a crude but useful seat form that can be trimmed and covered with fabric-reinforced tape to fashion a functional form-fitting seat. Drawbacks of this method are: (1) That the wrinkles that unavoidably form in the bag create airpockets that become voids during foaming. (2) Shaping the foam removes its skin, exposing a softer, less resilient composition that is not as durable. (3) The finished result lacks the quality appearance desirable in a custom racing vehicle. (4) Very little desirable positive pressure-support of the body is created as the foam is effectively allowed to expand virtually in all directions under the body.
In competition vehicles where sufficient room is present to allow the installation of specially-fabricated racing seats, the seats typically have rigid shells formed of aluminum or glass fiber. Only available in limited sizes meant to accomodate the greatest number of body shapes, their designs are anatomically crude and often simplified for ease of manufacturing and/or mounting to the vehicle.
The glass fiber variations can have smooth curves and are often used without padding of any kind, but glass fiber types with overlaid thinly-padded seat covers, either glued-in or removable, are also available. Aluminum seats, although rated stronger than the glass fiber type, are the least anatomically accurate due to their difficulty of fabrication. They are formed from bent and welded sheet (typical thickness 0.081-0.125 inch) into boxy shapes that have a virtually flat surface to support the back, a bottom panel formed in a shallow angle to support the buttocks and upper thighs, and flat side panels that can be bent over the rib cage to limit side-to-side movement of the body. Aluminum seats typically incorporate upholstery of thin foam padding covered with expanded vinyl or fabric that is either glued-in-place or in a slip-on style that secures with snaps. Both the glass fiber and aluminum types fit poorly compared with a custom seat contoured to an individual driver's body.
The effect of any seat that does not conform precisely to the unique configuration of an individual driver's body is to heavily concentrate dynamic loads on the points of the body closest in proximity to the contours of the seat in question. In practice, this can lead to forces many times the driver's own weight being concentrated over small areas on the body such as the high spots on the hip bones, rib cage, etc. Severe bruising and even bleeding at the hips, and brusied and broken ribs are not uncommon in racing drivers, even without accidents or collisions.
Previous patents regarding seating have been largely in two areas: First are methods to produce passenger-car-type seating by more efficient mass-production techniques, none of which lend themselves economically to the creation of individualized custom seating. Second are methods concerned with seating for handicapped or disabled persons confined to wheelchairs where the object is comfort during prolonged immobility.
The body-shaped cushions devised for wheelchair application are the nearest reference to form-fitting seating. U.S. Pat. No. 3,830,896 to Contourpedic Corp. (Jun. 8, 1972) and U.S. Pat. No. 4,615,856 to Silverman (Jul. 29, 1985) propose the use of styrene pellets to obtain a primary mold, similar to the first of the racing methods described above.
U.S. Pat. No. 4,753,480 to Morell (May 14, 1987) proposes a technique for assembling resilient foam material into cushioning pads of varying density. This system does not produce a true form-fit and, as mentioned, cushioning in general allows misalignment of the driver to the controls and deprives the driver of critical sensory feeback needed to approach the vehicle's limits of performance.
U.S. Pat. No. 4,828,325 to University of Tennessee Research Corp. (Sep. 29, 1987) proposes a technique for producing elastic seat and back cushions for assembly into a wheelchair frame that are molded to the body of the patient. Again, the described deep cushioning, desirable in a wheelchair, is not desirable in a racing vehicle. Also, the specialized mold boxes do not lend themsleves to the often-cramped confines of a racing vehicle where keeping the driver as low as possible in the vehicle to reduce the overall center of gravity can be essential. Separate seat and back cushion sections requiring separate molding operations while maintaining matching body positions, special foam injection fittings, hydrocarbon blowing equipment, heat sensors, and a knowledge of foam chemistry sufficient to limit the temperature of the reacting mixture below what a subject being molded could tolerate all tend to limit the technique to expensive specialists. Furthermore, the sling arrangement suggested for placing the person to be molded in suspension over the reacting foam will itself alter the ideal shape of the body to be supported by the cushion thus created.